Hayward H400 manifold spacing

[Psiuyo]

So, this happened last spring and again this past weekend, but after moderate rain my heater won't stay on fire more than a minute and after a few attempts eventually throws an if code.
Now, I've been able to resolve this by simply removing the 4 screws holding the manifold to the air box and separating it from the foam gasket. This provides maybe 1/8 inch separation at the right end and I'm guessing allows more air around the gas nozzles. Starts up right away and operates completely normal in this state.
Last year, after a couple months like this I screwed everything back down and it continued to work properly until this past weekend. Removed the screws again, and if to the races.
My question is, why is this necessary during this wet/damp season and is they any harm in putting some washers in place and leaving it slightly separated permanently?

 

[swamprat69]

How old is your heater? Has it ever been cleaned by a qualified technician? The "air box" is meant to be sealed (that is why it has a gasket). The heater was designed and approved to operate as it came in the box. There could be many different things (parameters) that could cause your symptoms. Have you observed the flame pattern through the observation port when the failure occurs? Has the flame sensor ever been cleaned? Humid air is less dense than dry air which could cause the failure if any of the operating parameters are on the edge of being adequate. I would not run the heater with the air box not sealed correctly as it may exacerbate an existing problem or cause new problems.